Stem cells refer to cells having the ability to self-replicate and the ability to differentiate into at least two cells and can be classified into totipotent stem cells, pluripotent stem cells, and multipotent stem cells.
Totipotent stem cells are cells with totipotent properties capable of developing into one perfect individual, and these properties are possessed by cells up to the 8-cell stage after the fertilization of an ovum by a sperm. When these cells are isolated and transplanted into the uterus, they can develop into one perfect individual.
Pluripotent stem cells, which are cells capable of developing into various cells and tissues derived from ectodermal, mesodermal and endodermal layers, are derived from an inner cell mass located inside blastocysts generated 4-5 days after fertilization. These cells are called embryonic stem cells and can differentiate into various other tissue cells but not create new living organisms.
Multipotent stem cells are stem cells capable of differentiating into only cells specific to tissues and organs containing these cells and are involved in the growth and development of each tissue and organ during fetal, neonatal, and adult periods as well as the maintenance of homeostasis of adult tissues and the induction of regeneration of damaged tissues. These tissue-specific multipotent cells are collectively referred to as adult stem cells. Adult stem cells are taken from pre-existing cells in various organs of the human body and then developed into stem cells, and these cells are characterized by differentiation into specific tissues. However, experiments for differentiating adult stem cells into various tissues such as hepatocytes have been performed successfully and thus have attracted much attention.
Stem cells have properties such as self-renewal, differentiation, and immortality, and adult stem cells, which can be obtained from various tissues, can be derived from various sources, compared to embryonic stem cells. Moreover, adult stem cells can avoid ethical issues that researchers can encounter and thus have been widely used in studies. Furthermore, stem cells isolated from umbilical cord blood do not cause any additional damage to a donor, unlike bone marrow or adipose tissue, and thus have more advantages than other adult stem cells.
Meanwhile, inflammatory brain diseases refer to inflammatory diseases occurring in the brain due to specific causes and encompass encephalitis, meningitis, meningoencephalitis, etc. Encephalitis is the generic term for inflammatory diseases of the cerebral parenchyma and is distinguished from inflammation of the meninges surrounding the brain (meningitis). When meningitis and encephalitis are both present, this is frequently referred to as meningoencephalitis. Depending on the causes, encephalitis can be broadly divided into infectious, vasculitic, tumoral, chemical, and idiopathic encephalitis and can be divided again into specific categories depending on the details.
Moreover, the encephalitis can be divided into acute, subacute, and chronic encephalitis depending on the time course of the disease. Until now, antibiotics have been used for the treatment of inflammatory brain diseases, but even if the causative organisms are treated by the use of antibiotics, they cause side effects such as acute brain injury, hydrocephalus, hypacusis, epilepsy, etc., and thus there is a need to develop a new treatment for inflammatory brain diseases. However, there have been no systematic studies on the treatment of inflammatory brain diseases using stem cells so far.
Accordingly, the present inventors have conducted research to develop a new medicine for treating inflammatory brain diseases and found that direct administration of stem cells into the ventricles of animal models with inflammatory brain diseases has excellent therapeutic effects on inflammatory brain diseases, such as causing less side effects such as significantly reduced brain injury due to inflammatory response such as edema and significantly reduced loss in weight, reducing the degree of apoptosis and reactive gliosis, and significantly reducing the number of activated macrophages and the number of inflammatory cytokines in the brain, thereby completing the present invention.